feat(hosting): add HostWizard platform module and fix migration chain

- Add complete hosting module (models, routes, schemas, services, templates, migrations)
- Add HostWizard platform to init_production seed (code=hosting, domain=hostwizard.lu)
- Fix cms_002 migration down_revision to z_unique_subdomain_domain
- Fix prospecting_001 migration to chain after cms_002 (remove branch label)
- Add hosting/prospecting version_locations to alembic.ini
- Fix admin_services delete endpoint to use proper response model
- Add hostwizard.lu to deployment docs (DNS, Caddy, Cloudflare)
- Add hosting and prospecting user journey docs to mkdocs nav

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/hosting/exceptions.py

@@ -0,0 +1,57 @@
+# app/modules/hosting/exceptions.py
+"""
+Hosting module exceptions.
+"""
+
+from app.exceptions.base import (
+    BusinessLogicException,
+    ResourceNotFoundException,
+)
+
+
+class HostedSiteNotFoundException(ResourceNotFoundException):  # noqa: MOD025
+    """Raised when a hosted site is not found."""
+
+    def __init__(self, identifier: str):
+        super().__init__(
+            resource_type="HostedSite",
+            identifier=identifier,
+        )
+
+
+class ClientServiceNotFoundException(ResourceNotFoundException):  # noqa: MOD025
+    """Raised when a client service is not found."""
+
+    def __init__(self, identifier: str):
+        super().__init__(
+            resource_type="ClientService",
+            identifier=identifier,
+        )
+
+
+class DuplicateSlugException(BusinessLogicException):  # noqa: MOD025
+    """Raised when trying to create a site with a slug that already exists."""
+
+    def __init__(self, slug: str):
+        super().__init__(
+            message=f"A hosted site with slug '{slug}' already exists",
+            error_code="DUPLICATE_SLUG",
+        )
+
+
+class InvalidStatusTransitionException(BusinessLogicException):  # noqa: MOD025
+    """Raised when attempting an invalid status transition."""
+
+    def __init__(self, current_status: str, target_status: str):
+        super().__init__(
+            message=f"Cannot transition from '{current_status}' to '{target_status}'",
+            error_code="INVALID_STATUS_TRANSITION",
+        )
+
+
+__all__ = [
+    "HostedSiteNotFoundException",
+    "ClientServiceNotFoundException",
+    "DuplicateSlugException",
+    "InvalidStatusTransitionException",
+]